1. Field of the Invention
The present invention relates to a motor structure, in particular, to a thin motor structure.
1. Description of the Related Art
Recently, it is a tendency to make electrical products thin and small. Notebooks and cellphones are examples. According to the development of thin electrical products, a thin fan motor structure is necessarily needed.
For a designer, it is not satisfied to develop a thin motor structure utilizing the stator structure of the conventional motor. In addition, there are difficulties in manufacturing a thin conventional stator structure.
FIG. 1 is a partial cross-sectional view showing a conventional motor structure. FIG. 2 is a front view showing the motor structure as shown in FIG. 1. Referring to FIGS. 1 and 2, the motor structure includes a magnet ring 100 and a stator 200. The magnet ring 100 is a part of a rotor (not completely shown). The stator 200 includes a set of silicon steel sheets 201 with four poles and coils (wirings) 202 wound on the silicon steel sheets 201.
Since each of the silicon steel sheets 201 composes a plurality of silicon steel sheets in a stack manner as shown in FIG. 2, the edges of the silicon steel sheets 201 are sharp. In this case, each of the silicon steel sheets 201 needs to be covered with a film or cover (not shown) so that the coils 202 can be wound without damage.
Moreover, since the circular areas surrounded by the silicon steel sheets 201 can not be totally filled by the coils, a lot of space is wasted and the performance of the motor deteriorates.
Accordingly, several problems that may occur in thinning a motor structure as described below must be resolved.
(a) The motor performance deterioration as a result of the decrease in the count of the silicon steel sheets and the space for winding coils.
(b) The manufacture and assembly difficulty of the motor as a result of the demand for small size and strict tolerance of the stator.
(c) The coils wound on the silicon steel sheets of a thin stator being apt to damage and short-circuit as a result of the relatively sharp edge of the silicon steel sheets.
(d) As far as the rotating stability of the motor is concerned, it is preferred to increase the number of poles configured on the motor. In this case, however, there exists difficulty in winding the coils. In addition, the motor may start with vibration and rotate with instability because the poles of motor are improperly configured.
In the above-mentioned problems, it is noted that the rotating stability is critical in the performance of a motor structure, especially a thin motor structure. Thus, it is important to design a thin motor structure that can easily start without vibration and rotate without instability. Therefore, the present invention intends to provide a motor structure that can be started without vibration, rotates without instability, and satisfies the demands for thinning.
It is therefore an object of the present invention to provide a thin motor structure having sufficient space for winding coils, and capable of facilitating the winding.
It is another object of the present invention to provide a thin motor structure having the merits of easy manufacture and assembly.
It is still another object of the present invention to provide a thin motor structure having a small and thin size stator which can be configured to facilitating the pole""s configuration of the motor.
It is still another object of the present invention to provide a thin motor structure capable of enabling the motor to start without vibration and to rotate without instability.
It is still another object of the present invention to provide a thin motor structure which can be easily started by utilizing the magnetic bias to balance the torque.
Accordingly, a motor structure according to the present invention comprises a stator and a rotor. The stator comprises a coil assembly, which includes a ring-shaped slot having an inner periphery on its inner side and an outer periphery on its outer side away from the inner periphery, a plurality of first teeth mounted around the inner periphery of the ring-shaped slot, and a plurality of second teeth mounted around the outer periphery of the ring-shaped slot; wherein each of the first teeth is arranged to partially trail behind the corresponding second tooth in a circumferential direction of the ring-shape slot. The rotor includes a circular magnet located above the coil.
In one aspect of the present invention, both the first teeth and the second teeth are selected as one configuration from a group consisting of chamfered teeth, teeth with round top corners, and teeth with indentations.
In another aspect of the present invention, the motor structure further comprises a base on which the coil assembly is mounted. In addition, a ring-shaped concavity is formed on the base.
In still another aspect of the present invention, the stator of the motor structure further comprises a static shaft substantially perpendicular to, and fixed on the base, and a ring-shaped groove being formed around the static shaft. The rotor of the motor structure further comprises a hub in which a through hole is formed; a metal sheet arranged between the hub and the circular magnet; and a bearing positioned in the through hole and being penetrated by the static shaft. In addition, the motor structure further comprises an engagement ring positioned in the through hole and on the bearing for fixing the bearing; and an elastic ring positioned in the ring-shaped groove for elastically fixing the bearing.